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C++ Fundamentals for Professionals

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Learn to apply all variations of the C++ string find function to search for substrings within strings. This lesson provides practical examples using two sample strings, preparing you for advanced string manipulation techniques covered in the next lesson.

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Solution

C++ 17
#include <iostream>
#include <string>
int main(){
  std::cout << std::endl;
  std::string str;
  
  // std::string::size_type idx= str.find("no");
  auto idx = str.find("no");
  if (idx == std::string::npos) std::cout << "no not found " << std::endl;
  
  std::cout << std::endl;
  
  str = {"dkeu84kf8k48kdj39kdj74945du942"};
  std::string str2{"84"};
  
  std::cout << "str: " << str <<  std::endl;
  std::cout << "str2: " << str2 << std::endl;
  
  std::cout << "str.find('8'): " << str.find('8') << std::endl;
  std::cout << "str.rfind('8'): " << str.rfind('8') << std::endl;
  std::cout << "str.find('8', 10): " << str.find('8', 10) << std::endl;
  std::cout << "str.find(str2): " << str.find(str2) << std::endl;
  std::cout << "str.rfind(str2): " << str.rfind(str2) << std::endl;
  std::cout << "str.find(str2, 10): " << str.find(str2, 10) << std::endl;
  
  std::cout << std::endl;
  
  str2 = "0123456789";
  std::cout << "str: " << str << std::endl;
  std::cout << "str2: " << str2 << std::endl;
  
  std::cout << "str.find_first_of(678): " << str.find_first_of("678") << std::endl;
  std::cout << "str.find_last_of(678): " << str.find_last_of("678") << std::endl;
  std::cout << "str.find_first_of(678, 10): " << str.find_first_of("678", 10) << std::endl;
  std::cout << "str.find_first_of(str2): " << str.find_first_of(str2) << std::endl;
  std::cout << "str.find_last_of(str2): " << str.find_last_of(str2) << std::endl;
  std::cout << "str.find_first_of(str2, 10): " << str.find_first_of(str2, 10) << std::endl;
  std::cout << std::endl;
  
  std::cout << "str: " << str << std::endl;
  std::cout << "str2: " << str2 << std::endl;
  
  std::cout << "str.find_first_not_of(678): " << str.find_first_not_of("678") << std::endl;
  std::cout << "str.find_last_not_of(678): " << str.find_last_not_of("678") << std::endl;
  std::cout << "str.find_first_not_of(678, 10): " << str.find_first_not_of("678", 10) << std::endl;
  std::cout << "str.find_first_not_of(str2): " << str.find_first_not_of(str2) << std::endl;
  std::cout << "str.find_last_not_of(str2): " << str.find_last_not_of(str2) << std::endl;
  std::cout << "str.find_first_not_of(str2, 10): " << str.find_first_not_of(str2, 10) << std::endl;
  
  std::cout << std::endl;
  
}

Explanation

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